CARACAS, March 30 (Reuters) - Venezuela’s Supreme Court said it would take over the opposition-led Congress’s role because the legislature is in “contempt,” sparking accusations that President Nicolas Maduro’s administration is becoming a dictatorship.

While the pro-Maduro court has annulled many of the National Assembly’s decisions since the opposition won a majority in late 2015, it had not directly taken over functions.

Late on Wednesday, however, it authorized Maduro to create oil joint ventures without congressional approval.

“We warn that as long as the situation of contempt in the National Assembly continues, this constitutional chamber guarantees that congressional functions will be exercised by this chamber or another chosen organ,” the court said in a ruling.

The dispute centers on three lawmakers banned over vote fraud accusations, which Maduro critics say is an excuse for the government to muzzle opposition during a mounting economic crisis in the oil-rich country.

The Democratic Unity umbrella opposition organization slammed the Supreme Court’s decision on Thursday, with several lawmakers accusing Maduro of acting like a dictator.

“This unconstitutional sentence that we reject ... cements another step in the dismantling of Venezuela’s democracy,” the opposition said in a statement.

“This government is dying, and that’s why it’s turning to these desperate measures.”

However, the measure may come as good news for some foreign oil companies in Venezuela that were spooked by the opposition’s warning that investment deals bypassing Congress would not be considered valid.

As Venezuela tries to raise funds while facing steep bond payments and a reeling economy, it has sought to sell stakes in oil fields.

State oil company PDVSA recently offered Russian oil major Rosneft a stake in the Petropiar oil joint venture, sources with knowledge of the proposal told Reuters this month. (Reporting by Corina Pons; Writing by Alexandra Ulmer; Editing by Andrew Cawthorne and Lisa Von Ahn)